U.S. patent application number 10/511589 was filed with the patent office on 2006-07-13 for deformed wire for reinforcing marine optical fiber cable.
Invention is credited to Hitoshi Demachi, Michiyasu Honda, Masatsugu Murao, Shoichi Ohashi.
Application Number | 20060154101 10/511589 |
Document ID | / |
Family ID | 29243247 |
Filed Date | 2006-07-13 |
United States Patent
Application |
20060154101 |
Kind Code |
A1 |
Ohashi; Shoichi ; et
al. |
July 13, 2006 |
Deformed wire for reinforcing marine optical fiber cable
Abstract
Deformed wire for a submarine optical fiber cable used for the
pressure-proof layer of the submarine optical cable and having a
high strength, that is, having a tensile strength of 1800 MPa or
more, is provided, which deformed wire for reinforcing submarine
optical fiber cable is characterized by including, by wt %, C: more
than 0.65% to 1.1%, Ceq=C+1/4Si+1/5Mn+4/13Cr satisfying
0.80%.ltoreq.Ceq.ltoreq.1.80%, having a number of shear bands
cutting across an L-section center axial line of 20/mm per unit
length of the center axis, having an angle formed by the center
axis and shear bands in the range of 10 to 90.degree., having a
tensile strength of 1800 MPa or more, having a sectional area
forming an approximately fan shape, a plurality of the
approximately fan shapes being combined to form a circular hollow
cross-section for accommodating optical fibers, having at its
surface a pebbled surface comprised of relief shapes of depths of
0.2 to 5 .mu.m, and having a weld at least at one location in the
longitudinal direction.
Inventors: |
Ohashi; Shoichi;
(Kamaishi-shi, JP) ; Demachi; Hitoshi;
(Chiyoda-ku, JP) ; Murao; Masatsugu;
(Higashiosaka-shi, JP) ; Honda; Michiyasu;
(Higashiosaka-shi, JP) |
Correspondence
Address: |
KENYON & KENYON LLP
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
29243247 |
Appl. No.: |
10/511589 |
Filed: |
January 14, 2003 |
PCT Filed: |
January 14, 2003 |
PCT NO: |
PCT/JP03/00216 |
371 Date: |
January 26, 2006 |
Current U.S.
Class: |
428/544 ;
140/2 |
Current CPC
Class: |
C22C 38/02 20130101;
G02B 6/4429 20130101; C22C 38/06 20130101; C21D 8/06 20130101; C22C
38/04 20130101; G02B 6/4427 20130101; Y10T 428/12 20150115; Y10S
148/909 20130101; C21D 9/50 20130101 |
Class at
Publication: |
428/544 ;
140/002 |
International
Class: |
B21C 47/26 20060101
B21C047/26; B22D 7/00 20060101 B22D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2002 |
JP |
2002-110807 |
Claims
1. Deformed wire for reinforcing submarine optical fiber cable
characterized by including, by wt %, C: more than 0.65% to 1.1%,
Si: 0.15 to 1.5%, and Mn: 0.20 to 1.5% and further including one or
two or more of Cr: 1.2% or less, where (Mn+Cr): 0.2 to 1.5%, Mo:
0.01 to 0.1%, V: 0.01 to 0.1%, Al: 0.002 to 0.1%, Ti: 0.002 to
0.1%, Nb: 0.001 to 0.3%, and B: 0.0005 to 0.1%, where a total of
(Mo+V+Al+Ti+Nb+B) is 0.0005 to 0.5%, and a balance of Fe and
unavoidable impurities, Ceq=C+1/4Si+1/5Mn+4/13Cr satisfying
0.80%.ltoreq.Ceq.ltoreq.1.80%, being a ferrite-pearlite structure
or pearlite structure, having a number of shear bands cutting
across an L-section center axial line (shear bands having
inclination with respect to rolling direction) of 20/mm per unit
length of the center axis, having an angle formed by the center
axis and shear bands in the range of 10 to 90.degree., having a
tensile strength of 1800 MPa or more, having a sectional area
forming an approximately fan shape, a plurality of the
approximately fan shapes being combined to form a circular hollow
cross-section for accommodating optical fibers, having at its
surface a pebbled surface comprised of relief shapes of depths of
0.2 to 5 .mu.m, and having a weld at least at one location in the
longitudinal direction.
2. Deformed wire for reinforcing submarine optical fiber cable
characterized by including, by wt %, C: more than 0.65% to 1.1%,
Si: 0.15 to 1.5%, and Mn: 0.20 to 1.5% and further including one or
two or more of Cr: 1.2% or less, where (Mn+Cr): 0.2 to 1.5%, Mo;
0.01 to 0.1%, V: 0.01 to 0.1%, Al: 0.002 to 0.1%, Ti: 0.002 to
0.1%, Nb: 0.001 to 0.3%, and B: 0.0005 to 0.1%, where a total of
(Mo+V+Al+Ti+Nb+B) is 0.0005 to 0.5%, and a balance of Fe and
unavoidable impurities, Ceq=C+1/4Si+1/5Mn+4/13Cr satisfying
0.80%.ltoreq.Ceq.ltoreq.1.80%, being a ferrite-pearlite structure
or pearlite structure, by having Si segregated so as to satisfy a
Si maximum segregation degree of the cementite/ferrite interface in
the range of 30 nm to the ferrite phase side from the cementite and
ferrite interface of the pearlite structure (maximum Si
concentration/Si content of bulk in range of 30 nm to ferrite phase
side from cementite and ferrite interface).gtoreq.1.1, having a
number of-shear bands cutting across an L-section center axial line
(shear bands having inclination with respect to rolling direction)
of 20/mm per unit length of the center axis, having an angle formed
by the center axis and shear bands in the range of 10 to
90.degree., having a tensile strength of 1800 MPa or more, having a
sectional area forming an approximately fan shape, a plurality of
the approximately fan shapes being combined to form a circular
hollow cross-section for accommodating optical fibers, having at
its surface a pebbled surface comprised of relief shapes of depths
of 0.2 to 5 .mu.m, and having a weld at least at one location in
the longitudinal direction.
Description
TECHNICAL FIELD
[0001] The present invention relates to deformed wire for
reinforcing submarine optical fiber cable.
BACKGROUND ART
[0002] As a structure of a submarine cable having optical fibers as
transmission lines, for example, ones of the structures shown in
FIG. 1 or FIG. 2 have been proposed.
[0003] These structures will be explained below. 1 is a bundle of
optical fibers obtained by twisting together a plurality of optical
fibers 1a or such a bundle buried in an ultraviolet curing
synthetic resin (ultraviolet curing urethane) or such a bundle
buried in a thermoplastic synthetic resin with a tension-bearing
member 1b passed through the center of the optical fibers. 2 is a
pressure-proof layer for protecting the optical fiber unit 1 from
water pressure, while 3 is a tension-bearing layer mainly formed by
twisting together steel wire (piano wire) so as to be able to
handle the tension applied to the cable.
[0004] This tension-bearing member layer 3 is made a single-layer
or multiple-layer structure, has a tension-bearing ability enabling
it to withstand the tensile load due to the weight of the cable
itself at the time of laying or retrieving the cable, and acts to
protect the cable from outside damage.
[0005] 4 is a metal layer air-tight with the bundle of the
tension-bearing member layer 3 and forming a power feed conduit to
a repeater. Normally, it is comprised of a metal tape made of
copper, aluminum, etc. attached longitudinally, welded together,
and reduced in diameter (shrunk) to form it into a tube.
[0006] Further, 5 and 6 are insulating layers (sheaths) meant for
insulation from the seawater and formed by low density and high
density polyethylene etc.
[0007] Among these cables, the one shown in FIG. 1 uses a
combination of three approximately fan-shaped deformed wires as the
pressure-proof layer 2. Further, in FIG. 2, the tension-bearing
member layer 3 is configured to form a pressure-proof shell by the
interaction of the tension-bearing wires wound in two layers.
[0008] The tension-bearing ability of the submarine optical cable
is mainly provided by the pressure-proof layer 2 and the
tension-bearing member layer 3. The tensile strength of the steel
wire (piano wire) used for the tension-bearing members 3 is of a
level of 2200 MPa. On the other hand, for the approximately
fan-shaped deformed wire used for the pressure-proof layer 2, as
high strength deformed wire for submarine optical cable using for
example wire rod for long, high tension steel wire superior in
weldability and cold workability, Japanese Examined Patent
Publication (Kokoku) No. 7-65142 proposes deformed wire with an
approximately fan-shaped cross-section having a tensile strength of
at least 1226 MPa produced from steel wire defined as
Ceq=C+(Mn+Cr)/5.gtoreq.0.57%. However, the maximum value of the
tensile strength achieved is on the level of 1520 MPa. This is
currently lower than the tensile strength of piano wire.
[0009] In recent years, an increased communication capacity has
been demanded from submarine cable systems. To meet with the
increase in communication capacity, higher performance of optical
fibers and an increased number of optical fibers accommodated in
submarine optical cable have been demanded.
[0010] Along with the increase in the number of optical fibers
accommodated, the optical fiber units have increased in outside
diameter. Therefore, the inside diameter of the pressure-proof
layer 2 has become greater. To prevent the cable outside diameter
from increasing along with this, the thickness of the
pressure-proof layer 2 has to be made smaller, so the
tension-bearing ability of the cable drops. If the tension-bearing
ability drops, since the tension-bearing ability is designed to
handle the tensile load due to the weight of the cable itself at
the time laying or retrieving the cable, there is the problem that
the tension-bearing ability of the cable has to be kept from being
exceeded by making the depth of use of the cable shallower.
[0011] On the other hand, if not changing the thickness of the
pressure-proof layer 2, the outside diameter of the pressure-proof
layer 2 becomes larger. In this case, there is the problem that
along with the increase in the outside diameter of the
pressure-proof layer 2, the tension-bearing ability of the cable
has to be kept from being exceeded by making the depth of use of
the cable shallower.
[0012] Further, along with an increase in the communication
capacity and an increase in the number of fibers, the processing
capability and number of amps required in the repeaters increase
and the amount of power supplied to the repeaters increase. A
repeater is supplied with power from a station on land through the
metal layer 4 serving as the power feed conduit. Along with an
increase in the amount of fed power, the voltage applied at the
station also becomes high, so a reduction in the conduction
resistance of the metal layer 4 forming the power feed conduit is
required. To reduce the conductor resistance of the metal layer 4,
it is necessary to increase the cross-sectional area of the metal
layer 4. This means an increase in the thickness of the metal layer
4, so the weight of the cable increases.
[0013] To solve the problem of an increase in the weight of the
cable or a decline in the tension-bearing ability being accompanied
with the depth of use of the cable becoming shallower, the
tension-bearing members of the cable have to be raised in
strength.
DISCLOSURE OF INVENTION
[0014] The present invention provides deformed wire for submarine
optical fiber cable using wire rod for long, high tension steel
wire superior in weldability and cold workability, used for the
pressure-proof layer 2 of the submarine optical cable, and high in
strength, that is, having a tensile strength of 1800 MPa or
more.
[0015] The present invention was made to achieve this object and
has as its gist the following:
[0016] (1) Deformed wire for reinforcing submarine optical fiber
cable characterized by including, by wt %, C: more than 0.65% to
1.1%, Si: 0.15 to 1.5%, and Mn: 0.20 to 1.5% and further including
one or two or more of Cr: 1.2% or less, where (Mn+Cr): 0.2 to 1.5%,
Mo: 0.01 to 0.1%, V: 0.01 to 0.1%, Al: 0.002 to 0.1%, Ti: 0.002 to
0.1%, Nb: 0.001 to 0.3%, and B: 0.0005 to 0.1%, where a total of
(Mo+V+Al+Ti+Nb+B) is 0.0005 to 0.5%, and a balance of Fe and
unavoidable impurities, Ceq=C+1/4Si+1/5Mn+4/13Cr satisfying
0.80%.ltoreq.Ceq.ltoreq.1.80%, being a ferrite-pearlite structure
or pearlite structure, having a number of shear bands cutting
across an L-section center axial line (shear bands having
inclination with respect to rolling direction) of 20/mm per unit
length of the center axis, having an angle formed by the center
axis and shear bands in the range of 10 to 90.degree., having a
tensile strength of 1800 MPa or more, having a sectional area
forming an approximately fan shape, a plurality of the
approximately fan shapes being combined to form a circular hollow
cross-section for accommodating optical fibers, having at its
surface a pebbled surface comprised of relief shapes of depths of
0.2 to 5 .mu.m, and having a weld at least at one location in the
longitudinal direction.
[0017] (2) Deformed wire for reinforcing submarine optical fiber
cable characterized by including, by wt %, C: more than 0.65% to
1.1%, Si: 0.15 to 1.5%, and Mn: 0.20 to 1.5% and further including
one or two or more of Cr: 1.2% or less, where (Mn+Cr): 0.2 to 1.5%,
Mo: 0.01 to 0.1%, V: 0.01 to 0.1%, Al: 0.002 to 0.1%, Ti: 0.002 to
0.1%, Nb: 0.001 to 0.3%, and B: 0.0005 to 0.1%, where a total of
(Mo+V+Al+Ti+Nb+B) is 0.0005 to 0.5%, and a balance of Fe and
unavoidable impurities, Ceq=C+1/4Si+1/5Mn+4/13Cr satisfying
0.80%.ltoreq.Ceq.ltoreq.1.80%, being a ferrite-pearlite structure
or pearlite structure, by having Si segregated so as to satisfy a
Si maximum segregation degree of the cementite/ferrite interface in
the range of 30 nm to the ferrite phase side from the cementite and
ferrite interface of the pearlite structure (maximum Si
concentration/Si content of bulk in range of 30 nm to ferrite phase
side from cementite and ferrite interface).gtoreq.1.1, having a
number of shear bands cutting across an L-section center axial line
(shear bands having inclination with respect to rolling direction)
of 20/mm per unit length of the center axis, having an angle formed
by the center axis and shear bands in the range of 10 to
90.degree., having a tensile strength of 1800 MPa or more, having a
sectional area forming an approximately fan shape, a plurality of
the approximately fan shapes being combined to form a circular
hollow cross-section for accommodating optical fibers, having at
its surface a pebbled surface comprised of relief shapes of depths
of 0.2 to 5 .mu.m, and having a weld at least at one location in
the longitudinal direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1(a) is a perspective view of a submarine cable formed
with a pressure-proof layer using approximately fan-shaped deformed
wires.
[0019] FIG. 1(b) is a sectional view of the same.
[0020] FIG. 2 is a sectional view of a submarine cable formed with
a pressure-proof layer using only piano wire.
[0021] FIG. 3 is a view of the effects on the workability of
approximately fan-shaped deformed wire by the content of Si and the
presence of Si in the ferrite phase in TS=2100 MPa class
approximately fan-shaped deformed wire.
[0022] FIG. 4 is a view of an example of measurement, by an AP-FIM,
of the state of distribution of Si in the pearlite structure of
approximately fan-shaped deformed wire of 0.82% C-1.02% Si-0.52%
Mn-0.0042% Al.
[0023] FIG. 5(a) and FIG. 5(b) are photos of L-section structures
of approximately fan-shaped deformed wire.
[0024] FIG. 6(a) and FIG. 6(b) are photos of examples of breaks
during working of approximately fan-shaped deformed wire.
[0025] FIG. 7 is a view of the effects on breaks of approximately
fan-shaped deformed wire by the number and angle of shear bands
cutting across the L-section center axial line of approximately
fan-shaped deformed wire.
BEST MODE FOR CARRYING OUT THE INVENTION
[0026] Below, the present invention will be described in
detail.
[0027] As explained above, to raise the strength of the
tension-bearing members of cable, the tensile strength of the
approximately fan-shaped deformed wire must be made at least 1800
MPa.
[0028] The tensile strength of approximately fan-shaped deformed
wire is determined by the tensile strength of the original wire rod
and the amount of cold working, but the biggest problem at the time
of producing approximately fan-shaped deformed wire is the breaks
occurring during working. Raising the strength without breaks is
the point of the present invention. According to studies of the
inventors, for example, it was learned that to produce
approximately fan-shaped deformed wire 2 for reinforcing the
submarine optical fiber cable shown in FIG. 1 while achieving a
higher strength and without breaks during working, it is important
to control the shear bands having inclination with respect to the
rolling direction. For this, for example, it is effective that the
total reduction rate be suppressed to not more than 85% in the case
of a tensile strength of the approximately fan-shaped deformed wire
of 1800 MPa and to not more than 80% in the case of 2000 MPa. To
satisfy these conditions, it is necessary that the tensile strength
of the rolled wire rod be at least 1100 MPa in the case of a
tensile strength of the approximately fan-shaped deformed wire of
1800 MPa and at least 1200 MPa in the case of 2000 MPa.
[0029] Further, the inventors discovered that breaks of the
approximately fan-shaped deformed wire during production occur due
to strain ageing arising due to the free carbon in solid solution
in the steel material and the free nitrogen in solid solution in
the steel material derived from the breakdown of cementite due to
the heat produced during cold working. Therefore, they studied
additional alloys for suppressing cementite breakdown due to the
heat of working and the optimal amounts of addition and as a result
discovered that adjusting the amount of Si present at the
cementite/ferrite interface in the ferrite was effective and,
together, that supplementary addition of alloy elements forming
carbides of Cr, Mo, V, Ti, and Nb further enabled the breakdown of
cementite during cold working to be suppressed.
[0030] Further, they discovered that reducing the nitrogen in the
steel material and immobilizing the unavoidable nitrogen in solid
solution by the carbides of Mo, Al, Ti, Nb, V, and B was effective
for suppressing strain ageing due to nitrogen.
[0031] Further, the above steel material is required to be superior
in strength and toughness, including at the welds, when welding and
cold working the original wire rods to form the approximately
fan-shaped deformed wire. The C, Si, Mn, and Cr added for the
purpose of raising the strength tend to form structures resulting
in deterioration of the cold workability of the mother material and
welds when the amounts added increase, so it is preferable to
define optimal ranges giving a balance of higher strength and cold
workability.
[0032] As explained above, in the present invention, ranges of the
component elements are defined to satisfy all of the requirements
of high strength and good weldability and cold workability. The
reasons for limitation of the ranges are explained below.
[0033] C is preferably lower from the viewpoint of the weldability,
but if 0.65% or less, a tensile strength of 1100 MPa or more cannot
be secured. On the other hand, if over 1.1%, the segregation in the
continuous casting process becomes greater and micromartensite and
pro-eutectoid cementite remarkably deteriorating the cold
workability occur in the rolled wire rods, so the C content is made
more than 0.65% to 1.1%.
[0034] Si is effective for strengthening the wire rods due to the
solid solution hardening action. If 0.15% or less, that effect
cannot be obtained. Further, if over 1.5%, the toughness is
degraded, so the range is made 0.15% to 1.5%.
[0035] In particular, to prevent breaks during deformed working, as
explained above, to suppress strain ageing due to C during the cold
working, the breakdown of cementite and the solid solution of C in
the ferrite during cold working have to be suppressed. For this
reason, it is necessary to make the content of Si 0.5% to 1.5% and
control the Si to be present so as to satisfy an Si maximum
segregation degree of the cementite/ferrite interface in the range
of 30 nm to the ferrite phase side from the cementite and ferrite
interface of the pearlite structure (maximum Si concentration/Si
content of bulk in range of 30 nm to ferrite phase side from
cementite and ferrite interface).gtoreq.1.1. FIG. 3 shows the
effect on the workability of approximately fan-shaped deformed wire
of the content of Si of approximately fan-shaped deformed wire with
a tensile strength of 2100 MPa and the state of presence of Si at
the ferrite phase. If in the range of the present invention, no
breaks occurs during working. Further, the state of distribution of
the Si segregation degree at the cementite/ferrite interface can be
measured and found by an AP-FIM etc. as shown in for example FIG.
4. In particular, when the tensile strength is 2000 MPa or more, it
is preferable to define the Si in the above range.
[0036] To make the Si efficiently segregate at the
cementite/ferrite interface, for example it is effective to raise
the pearlite transformation temperature to an extent where no rough
cementite causing the wire drawing to degrade is precipitated,
prolong the time until the end, and increase as much as possible
the amount of Si discharged to the ferrite phase side at the time
of cementite precipitation. For this, it is effective to reduce the
cooling rate of the air blast cooling after rolling the wire rod to
not more than 1 to 10.degree. C.
[0037] Mn is an element with little effect on the weldability,
increasing the strength, immobilizing the S as sulfide, and
suppressing the heat embrittlement during rolling of the wire rod
and is preferably added to the allowable range. If Mn is less than
0.2%, it is not possible to immobilize the S as a sulfide or 1100
MPa or more of tensile strength of the wire rod cannot be secured.
On the other hand, if over 1.5%, the quenchability of the wire rod
becomes too high, micromartensite is produced, and the workability
is remarkably degraded in some cases, so the content was limited to
the range of 0.2% to 1.5%.
[0038] Cr is an element having exactly the same actions as Mn. It
is possible to replace part of the Mn by adding this. Further, in
addition to making the pearlite finer and raising the strength of
the wire rod, as explained above, this is an element forming
carbide and promoting stability of the cementite. If Cr is more
than 1.2% and further the total of Mn and Cr is over 1.5%,
micromartensite is produced, so Cr is limited to not more than 1.2%
and (Cr+Mn) to the range of 0.2 to 1.5%.
[0039] Mo, Al, V, Ti, Nb, and B are all elements adjusting the
.gamma.-granularity and also, as explained above, forming carbides
and nitrides and promoting the stability of cementite and
immobilization of the solid solution nitrogen. With Mo: less than
0.01%, Al: less than 0.002%, V: less than 0.01%, Ti: less than
0.002%, Nb: less than 0.001%, and B: less than 0.0005% and the
total of (Mo+V+Al+Ti+Nb+B) of less than 0.00051 of the one or two
or more types of the same, the effect cannot be obtained. With Mo:
more than 0.1%., Al: more than 0.1%, V: more than 0.1%, Ti: more
than 0.1%, Nb: more than 0.3%, and B: more than 0.1% and the total
of one or two or more types of over 0.5%, the effect is saturated
and the toughness degraded, so the total of the one or two or more
types of Mc: 0.01 to 0.1%, V: 0.01 to 0.1%, Al: 0.002 to 0.1X, Ti:
0.002 to 0.1%, Nb: 0.001 to 0.3%, and B: 0.0005 to 0.1% was limited
to 0.0005 to 0.5%.
[0040] P and S are both preferably not more than 0.03% from the
viewpoint of degradation of the toughness. N is preferably
suppressed to not more than 0.01% from the viewpoint of suppression
of ageing.
[0041] The strength of the original wire rod is determined by
Ceq=C+1/4Si+l/5Mn+4/13Cr and the cooling rate of the wire rod from
the austenite region. The higher the Ceq and the higher the cooling
rate, the greater the strength of the wire rod, but according to
studies by the inventors, it was learned that unless Ceq is 0.80%
or more, a wire rod having a strength of 1100 MPa or more cannot be
obtained, so Ceq was limited to 0.80% at a tensile strength of the
approximately fan-shaped deformed wire or 1800 MPa or more. This is
because with a Ceq lower than this, to secure the strength of the
wire rod, a need arises to make the cooling rate of the wire rod
extremely fast and therefore precipitation of bainite or martensite
harmful to the cold workability cannot be avoided.
[0042] Further, with a Ceq of more than 1.80%, the quenchability of
the wire rod rises and even if the cooling rate of the wire rod is
adjusted, bainite and martensite harmful to the cold workability
are precipitated and the workability is remarkably degraded, so
1.80% was made the upper limit.
[0043] When drawing a wire into a round wire by a die, a fiber
structure aligned in the axial direction develops. When producing
approximately fan-shaped deformed wire, in general, since rollers
having approximately fan-shaped calibers are used for cold rolling,
as shown in FIG. 5, in addition to the structure aligned parallel
to the axial direction, shear bands 10 having inclinations with
respect to the rolling direction are formed. The pearlite lamellar
spacings of the shear bands 10 are much finer than the lamellar
spacings of the pearlite aligned in the rolling direction. The
working strain therefore concentrates locally. Therefore, when the
ductility of the shear bands 10 is lower than the surroundings, in
the worst case, breaks 13 occur starting from the shear bands 10
during the working. Further, this becomes a cause of a drop in
ductility of the approximately fan-shaped deformed wire itself.
Therefore, the presence has to be reduced as much as possible. Even
when unavoidably present, it is important that the angle 12 formed
by the shear bands 10 and the center axis 11 not become an
extremely small angle. A small angle would mean that the state of
deformation at the outside diameter side and inside diameter side
of the approximately fan shape during rolling would become greatly
different and strain would concentrate at the shear bands more and
the ductility would drop. As shown in FIG. 7, it is possible to
suppress breaks during working by making the number of shear bands
cutting across the L-section center axial line 11 of the
approximately fan-shaped deformed wire not more than 20/mm per unit
length of the center axis 12 and making the angle formed by the
center axis 11 and shear bands the range of 10 to 90.degree..
Further, the inclination of the shear bands sometimes is toward the
rolling direction and sometimes toward the opposite direction
depending on the caliber conditions of the cold rolling, but the
angle formed by the shear bands and center axis is set so that the
smaller angle is in the range of 10 to 90.degree. regardless as to
the rolling direction.
[0044] As a technique for suppressing the occurrence of such shear
bands 10, for example, as explained above, it is possible to reduce
the total reduction rate along with the rise in the strength of the
approximately fan-shaped deformed wire. However, in the
conventionally commercialized 5.0 mm diameter wire rod, there are
limits to reduction of the reduction rate at the time of cold
working. By cold working wire rods of diameters of less than 5.0
mm, for example, 4.5 mm, 4.0 mm, and 3.0 mm, to produce
approximately fan-shaped deformed wire, the reduction rate can be
reduced. Further, by the effect of the increase of the amount of
working during rolling of the wire rod by making the diameter not
more than 5.0 mm, the .gamma.-granularity becomes finer and the
granularity can be reduced to #8 or better in terms of the
.gamma.-granularity number. An effect of improvement of the
ductility is exhibited more than by just reducing the reduction
rate. Further, as explained above, adjusting the amount of addition
of Si and suppressing the strain ageing during wire drawing are
also effective.
[0045] Further, to suppress the occurrence of shear bands 10 and
control the angle 12, it is effective to adjust the caliber shapes
of the upper and lower rolling rollers so that the relative speeds
between the outside diameter side and inside diameter side of the
substantial fan shapes do not become very different.
[0046] Further, the example of the break of FIG. 6 shows the case
where the angle of the shear bands satisfies the range of the
present invention, but the number of shear bands is 24.3/mm per
unit length or over the range of the present invention. This
results in the break.
[0047] As explained above, to produce submarine cable having a
total length of about 50 to 100 km, when deeming, as a composition
having a good weldability and a good workability over the entire
length, including welds, in a 2t unit weight wire rod and securing
a strength of at least the 1800 MPa class when working the rod to
approximately fan-shaped deformed wire, Ceq=C+1/4Si+1/5Mn+4/13Cr,
it is effective to adjust Ceq to a range of 0.80%.to 1.80%.
[0048] Further, the welds and their vicinity are heated to at least
the A.sub.1 point, then rapidly cooled, so with just welding, the
result would be a hard martensite structure and the cold
workability would remarkably be degraded, therefore after welding,
heat treatment is necessary to reheat the welds to the austensite
region again and cool them.
[0049] For example, as the reinforcing pressure upset welding
conditions, the wire rod is heated under conditions of the A.sub.1
point temperature+50.degree. C. or more at a wire rod diameter D
(unit: mm) for at least 5.times.D (unit: sec), then subjected to
the reinforcing pressure upset welding. The weld is reheated in a
temperature range of the A.sub.1 point temperature+50.degree. C. or
more to +300.degree. C. or more at the wire rod diameter D (unit:
mm) for a heating time of 5.times.D (unit: sec) or more.
Alternatively, after reheating at the time of annealing, the wire
rod is preferably cooled under conditions of a cooling rate of 3 to
20.degree. C./sec in the range of the nose temperature of the TTT
curve to the nose temperature of the TTT curve+50.degree. C., then
held for at least 5 seconds to not more than 5 minutes in the range
of the nose temperature of the TTT curve to the nose temperature of
the TTT curve+50.degree. C., then cooled at a cooling rate of at
least 3.degree. C./sec.
[0050] In welding of wire rod, the problem becomes securing a
structure achieving the above mentioned target in the annealing
process after welding. In general, after butt welding, the weld is
reheated.to the .gamma.-region, then the cooling rate is controlled
for cooling and the annealing is performed. At this time, if the
Ceq is less than 0.80%, a structure with a good weldability and
workability can be secured, but a wire rod having a strength of the
weld of at least 1100 MPa cannot be obtained and a tensile strength
of the approximately fan-shaped deformed wire of 1800 MPa or more
cannot be secured, so the Ceq was limited to 0.80%. With a Ceq
lower than this, to secure the strength of the wire rod, a need
arises to raise the cooling rate at the time of annealing to an
extremely high level and precipitation of bainite and martensite
harmful to cold workability is unavoidable.
[0051] Further, with a Ceq over 1.80%, the quenchability of the
wire rod rises and even if adjusting the cooling rate at the time
of annealing, bainite and martensite harmful to the cold
workability precipitate and the workability of the welds is
remarkably degraded, so the limit was made 1.80%.
[0052] Further, as other methods for welding the rolled wire rod to
make long wire rod, there are the reinforcing pressure upset
method, TIG method, laser method, etc., but the method is not
particularly limited.
[0053] However, heat-affected zones unavoidably arise even with
heat treatment after welding, so the lamellar cementite breaks down
and forms spheres due to the heat effect. Even at the stage of wire
rod, the strength is low compared with the mother material.
Further, the amount of work hardening during the cold working is
low. Therefore, the difference in strength between the mother
material and the heat-affected zones of the deformed wire becomes
greater than the difference in strength between the mother material
and the heat-affected zones at the stage of wire rod. This trend
becomes remarkable as the approximately fan-shaped deformed wire
becomes higher in strength.
[0054] As the means for solving these problems, for example, it is
effective to weld the billets before rolling into wire rod at the
temperature of the austenite region right after heating at the
heating furnace, then roll to wire rod. There are then almost no
problems of the heat effect due to hot welding the billets. By
producing approximately fan-shaped deformed wire from over 2t large
unit weight wire rod coils with uniform structure and mechanical
properties, the variation in mechanical properties of the deformed
wire can be greatly reduced.
[0055] As the method for hot welding the billets, the flash butt,
reinforcing pressure upset, TIG, laser, or other method may be
used, but this is not particularly limited. If considering
guarantee of a drop in temperature of the billet at the time of
welding, it is necessary to weld after heating to at least
1000.degree. C.
[0056] The cable for a submarine cable, as shown in the above FIG.
1, prevents running of water by filling the clearance between the
optical fiber unit 1 and pressure-proof layer 2 or the
pressure-proof layer 2 and the metal layer 4 with a compound. Here,
for example, as shown in FIG. 1, if the inner circumference 9 of
the approximately fan-shaped deformed wire 2 is given a pebbled
finish, the coefficient of friction with the compound increases and
the ability to prevent running of water is improved.
[0057] Further, if the side faces 8 of the approximately fan-shaped
deformed wire 2 are worked to a pebbled finish, when combining
approximately fan-shaped deformed wires to form the pressure-proof
layer, the structural stability of the pressure-proof layer is
increased.
[0058] This pebbled surface has relief shapes of depths of about
0.2 to 5 .mu.m and is imparted by giving the roll surface in the
final step of the process of production of the approximately
fan-shaped deformed wire a pebbled surface or shot blasting the
surface of the deformed wire.
[0059] Further, as to the number of the approximately fan-shaped
deformed wires, FIG. 1 shows the fan shapes when dividing a circle
into three equal parts, but the invention is not limited to
division into three equal parts. It is possible to provide a
plurality of divided fan shapes according to the application and
conditions of use. Further, two to 1.0 fan shapes are desirable
from the industrial standpoint.
EXAMPLES
Example 1
[0060] The deformed wire for reinforcing submarine optical cable
having the above characteristics is obtained by for example heating
to 1050.degree. C. 2t unit weight billets containing 0.82% C-1.0%
Si-0.50% Mn-0.0045% Al (Ceq=1.23%), then flash butt welding two
billets hot, then rolling them to a diameter of 4.0 mm and air
blast cooling at 7.degree. C./s or so to obtain a unit weight 4t
wire rod coil adjusted to a tensile strength of 1300 MPa. Next, the
scale is removed, then the wire rod is given a phosphor zinc
coating, drawn by a die to 3.0 mm, then hot rolled by rollers to a
rectangular cross-section wire rod of a thickness of 1.8 mm. Next,
to obtain the substantial fan shape, the wire rod is cold rolled by
rollers having approximately fan shaped caliburs to obtain an
approximately fan-shaped deformed wire 2 of a length of 60 km
having an outside diameter b: 5.2 mm, inside diameter a: 2.55 mm,
thickness t: 1.325 mm, tensile strength 1820 MPa, and pebbled
surface relief depth of an average 1 .mu.mm such as shown in the
submarine optical fiber cable of FIG. 2. There are no shear bands
in the L-section microstructure of this approximately fan-shaped
deformed wire.
[0061] Table 1 to Table 6 (Table 2 to Table 6 are continuations of
Table 1) show the compositions, the Ceq, and the TS of the wire
rod, the workability when working the wire rod to deformed wire,
the strength of the deformed wire, the number of deformed wires
forming the protective layer, etc. TABLE-US-00001 TABLE 1 Test
Chemical composition (%) No. C Si Mn Cr Mn + Cr Ceq Al Ti Mo V Nb B
V + Al + Ti + Mo + Nb + B Invention examples 1 0.67 0.22 0.80 0.80
0.89 0.042 0.042 2 0.72 0.20 0.75 0.75 0.92 0.044 0.044 3 0.82 0.21
0.77 0.77 1.03 0.035 0.035 4 0.93 0.19 0.72 0.72 1.12 0.038 0.038 5
1.04 0.22 0.75 0.75 1.25 0.040 0.040 6 0.82 0.22 0.50 0.24 0.74
1.05 0.039 0.039 7 0.82 0.19 0.22 0.72 0.94 1.13 0.025 0.025 8 0.81
0.19 0.75 0.75 1.01 0.015 0.015 9 0.79 0.22 0.75 0.75 1.00 0.022
0.020 0.042 10 0.82 0.24 0.73 0.73 1.03 0.035 0.043 0.079 11 0.83
0.24 0.65 0.65 1.02 0.032 0.055 0.087 12 0.80 0.23 0.63 0.63 0.98
0.031 0.052 0.083 13 0.82 0.21 0.62 0.62 1.00 0.033 0.043 0.076 14
0.83 0.19 0.64 0.64 1.01 0.025 0.015 0.045 0.055 0.140 15 0.80 0.22
0.65 0.65 0.99 0.035 0.065 0.035 0.135 16 0.79 0.23 0.68 0.68 0.98
0.033 0.042 0.042 0.117 17 0.83 0.25 0.62 0.62 1.02 0.022 0.015
0.035 0.052 0.045 0.004 0.173 18 0.92 0.21 0.77 0.77 1.13 0.035
0.035 19 0.92 0.21 0.77 0.77 1.13 0.035 0.035 20 0.92 0.21 0.77
0.77 1.13 0.035 0.035 21 0.92 0.21 0.77 0.77 1.13 0.035 0.035 22
0.92 0.21 0.77 0.77 1.13 0.035 0.035 23 0.92 0.21 0.77 0.77 1.13
0.035 0.035 24 0.92 0.21 0.77 0.77 1.13 0.035 0.035 25 0.92 0.21
0.77 0.77 1.13 0.035 0.035 26 0.92 0.65 0.53 0.53 1.19 0.045 0.045
27 0.92 1.20 0.52 0.52 1.32 0.043 0.043 28 0.92 1.45 0.53 0.53 1.39
0.041 0.041 29 0.92 1.00 0.32 0.21 0.53 1.30 0.039 0.039 30 0.92
1.00 0.32 0.21 0.53 1.30 0.039 0.039 31 0.92 1.00 0.32 0.21 0.53
1.30 0.039 0.039 32 0.92 1.00 0.32 0.21 0.53 1.30 0.039 0.039
[0062] TABLE-US-00002 TABLE 2 Properties of wire rod Wire TS of
Structure TS of Structure Test dia. wire rod of wire weld of No.
(mm) (MPa) rod Welding means (MPa) weld Invention examples 1 6.30
1131 .alpha. + P Reinforcing 1118 .alpha. + P pressure upset 2 6.00
1176 P Reinforcing 1162 P pressure upset 3 5.00 1298 P Laser 1279 P
4 4.50 1410 P Laser 1388 P 5 4.00 1552 P Flash butt 1524 P 6 5.00
1325 P Flash butt 1306 P 7 5.00 1399 P TIG 1379 P 8 5.50 1247 P TIG
1231 P 9 5.50 1262 P Reinforcing 1246 P pressure upset 10 5.00 1342
P Reinforcing 1323 P pressure upset 11 5.00 1345 P Laser 1326 P 12
5.00 1303 P Laser 1284 P 13 5.00 1309 P Flash butt 1290 P 14 5.00
1386 P Flash butt 1366 P 15 5.00 1359 P TIG 1340 P 16 5.00 1339 P
TIG 1319 P 17 5.00 1432 P Reinforcing 1411 P pressure upset 18 4.50
1412 P Reinforcing 1390 P pressure upset 19 4.50 1412 P Laser 1390
P 20 4.50 1412 P Laser 1390 P 21 4.50 1412 P Flash butt 1390 P 22
4.50 1412 P Flash butt 1390 P 23 4.50 1412 P TIG 1390 P 24 4.50
1412 P TIG 1390 P 25 4.50 1412 P BT hot weld 1412 P 26 5.50 1422 P
Reinforcing 1404 P pressure upset 27 5.50 1435 P Reinforcing 1416 P
pressure upset 28 5.50 1457 P Laser 1438 P 29 5.50 1417 P Laser
1399 P 30 4.00 1418 P Flash butt 1393 P 31 3.50 1419 P Flash butt
1390 P 32 3.00 1420 P TIG 1386 P *Structure codes: .alpha.:
ferrite, P: pearlite, pro-e .theta.: pro-eutectoid cementite, B:
bainite, M: martensite
[0063] TABLE-US-00003 TABLE 3 Properties of deformed wire Si No. of
deformed segregation Reduction wires forming degree of No. of Angle
of Test OD ID rate TS EL protective .alpha./.theta. shear shear
Work- No. (mm) (mm) (%) (MPa) (%) layer interface bands bands
ability Invention examples 1 5.20 2.55 82.6 1830 3.2 3 -- 13 42
Good 2 5.20 2.55 80.8 1836 3.3 3 -- 11 43 Good 3 5.20 2.55 72.3
1812 3.1 3 -- 7 48 Good 4 5.20 2.55 65.8 1840 3.2 3 -- 0 45 Good 5
5.20 2.55 56.8 1887 3.0 3 -- 0 43 Good 6 5.20 2.55 72.3 1839 2.9 3
-- 7 42 Good 7 5.20 2.55 72.3 1913 2.9 3 -- 8 42 Good 8 5.20 2.55
77.1 1837 3.2 3 -- 7 45 Good 9 5.20 2.55 77.1 1852 3.2 3 -- 8 39
Good 10 5.20 2.55 72.3 1856 3.3 3 -- 8 38 Good 11 5.20 2.55 72.3
1859 3.1 3 -- 7 43 Good 12 5.20 2.55 72.3 1817 3.2 3 -- 8 42 Good
13 5.20 2.55 72.3 1823 3.0 3 -- 8 41 Good 14 5.20 2.55 72.3 1900
3.1 3 -- 7 45 Good 15 5.20 2.55 72.3 1873 3.2 3 -- 8 46 Good 16
5.20 2.55 72.3 1852 3.0 3 -- 6 48 Good 17 5.20 2.55 72.3 1946 2.9 3
-- 8 43 Good 18 5.20 2.55 65.8 1842 3.1 3 -- 8 17 Good 19 5.20 2.55
65.8 1842 3.1 3 -- 8 28 Good 20 5.20 2.55 65.8 1842 3.1 3 -- 8 58
Good 21 5.20 2.55 65.8 1842 3.1 3 -- 8 65 Good 22 5.20 2.55 65.8
1842 3.1 3 -- 8 72 Good 23 5.20 2.55 65.8 1842 3.1 3 -- 3 42 Good
24 5.20 2.55 65.8 1842 3.1 3 -- 17 43 Good 25 5.20 2.55 65.8 1842
3.1 3 -- 16 47 Good 26 5.20 2.55 77.1 2012 2.8 3 1.22 12 35 Good 27
5.20 2.55 77.1 2025 2.9 3 1.34 4 39 Good 28 5.20 2.55 77.1 2047 3.1
3 1.56 3 32 Good 29 5.20 2.55 77.1 2007 3.0 3 1.43 6 36 Good 30
5.20 2.55 78.6 2035 3.0 6 1.52 6 31 Good 31 5.20 2.55 79.1 2045 3.0
8 1.77 7 29 Good 32 5.20 2.55 77.3 2013 3.0 10 1.83 5 26 Good
[0064] TABLE-US-00004 TABLE 4 Test Chemical composition (%) No. C
Si Mn Cr Mn + Cr Ceq Al Ti Mo V Nb B V + Al + Ti + Mo + Nb + B Comp
Ex. 33 0.60 0.25 0.54 0.54 0.77 0.036 0.036 34 1.12 0.25 0.88 0.88
1.36 0.042 0.042 35 0.82 1.64 0.55 0.55 1.34 0.041 0.041 36 0.82
0.25 1.00 0.67 1.67 1.29 0.042 0.042 37 0.82 1.03 0.53 0.53 1.18
0.042 0.025 0.230 0.160 0.230 0.007 0.694 38 0.82 0.25 0.95 0.95
1.07 0.042 0.042 39 0.82 0.22 0.92 0.92 1.06 0.041 0.041 40 0.82
0.24 0.91 0.91 1.06 0.043 0.043 41 0.82 1.01 0.47 0.47 1.17 0.040
0.040
[0065] TABLE-US-00005 TABLE 5 Properties of wire rod Wire TS of
Structure TS of Structure Test dia. wire rod of wire Welding weld
of No. (mm) (MPa) rod means (MPa) weld Comp. Ex. 33 6.80 995
.alpha. + P TIG 984 .alpha. + P 34 5.00 1478 P + pro-e.theta.
Reinforcing 1499 P + pressure pro-e.theta. + M upset 35 5.00 1452 P
+ B Reinforcing 1473 P + M pressure upset 36 5.00 1473 P + M Laser
1494 P + M 37 5.50 1428 P + M Laser 1447 P + M 38 5.50 1343 P Flash
butt 1326 P 39 5.50 1328 P Flash butt 1311 P 40 5.50 1333 P TIG
1316 P 41 5.50 1440 P TIG 1421 P *Structure codes: .alpha.:
ferrite, P: pearlite, pro-e .theta.: pro-eutectoid cementite, B:
bainite, M: martensite
[0066] TABLE-US-00006 TABLE 6 Properties of deformed wire Si No. of
deformed segregation Reduction wires forming degree of No. of Angle
of Test OD ID rate TS EL protective .alpha./.theta. shear shear
Work- No. (mm) (mm) (%) (MPa) (%) layer interface bands bands
ability Comp. Ex. 33 5.20 2.55 85.0 1755 3.2 3 -- 5 43 Good 34 5.20
2.55 72.3 1992 1.2 3 -- 25 43 Breakage 35 5.20 2.55 72.3 1966 1.6 3
-- 7 42 Breakage 36 5.20 2.55 72.3 1987 1.5 3 1.83 9 42 Breakage 37
5.20 2.55 77.1 2018 1.7 3 1.83 7 37 Breakage 38 5.20 2.55 77.1 1934
1.2 3 -- 29 39 Breakage 39 5.20 2.55 77.1 1918 1.5 3 -- 9 8
Breakage 40 5.20 2.55 77.1 1924 2.1 3 -- 31 6 Breakage 41 5.20 2.55
77.1 2130 0.7 3 1.03 8 39 Breakage
[0067] Nos. 1 to 32 are examples of the present invention, while
the rest are comparative examples. According to present invention,
excellent workability of the wire rod is secured and approximately
fan-shaped deformed wire of over the 2000 MPa class can be
produced.
[0068] As shown in Comparative Example No. 33, when the Ceq is
lower than the range of the present invention, if trying to
suppress breaks by making the total reduction rate not more than
85%, it is not possible to secure a strength of the approximately
fan-shaped deformed wire of 1800 MPa or more.
[0069] As shown in Comparative Example No. 34, when the C is higher
than the range of the present invention, the workability, including
the welds, becomes remarkably degraded and approximately fan-shaped
deformed wire cannot be stably produced.
[0070] As shown in Comparative Example No. 35, when the Si is
higher than the range of the present invention, the workability,
including the welds, becomes remarkably degraded and approximately
fan-shaped deformed wire cannot be stably produced.
[0071] As shown in Comparative Example No. 36, when the (Mn+Cr) is
higher than the range of the present invention, the workability,
including the welds, becomes remarkably degraded and approximately
fan-shaped deformed wire cannot be stably produced.
[0072] As shown in Comparative Example No. 37, even when the Ceq is
in the range, if the total of Al, Ti, Mo, V, Nb, and B is higher
than the range, the workability becomes remarkably degraded and
approximately fan-shaped deformed wire cannot be stably
produced.
[0073] As shown by Comparative Examples 33 to 37 above, if the
composition is outside the range of the present invention, high
strength approximately fan-shaped deformed wire cannot be stably
produced.
[0074] As shown in Comparative Example No. 38, when the shear band
angle in the approximately fan-shaped deformed wire is greater than
the range of the present invention, as shown in Comparative Example
No. 39, when the shear band angle is lower than the range of the
present invention, and as shown in Comparative Example No. 40, when
the number of the shear bands in the approximately fan-shaped
deformed wire and the shear band angle are both outside the range
of the present invention, the wire rod frequently breaks during
working and the approximately fan-shaped deformed wire cannot be
stably produced.
[0075] As shown by Comparative Examples 38 to 40 above, even if the
composition is in the range of the present invention, if the number
or angle of the shear bands in the microstructure is outside the
range of the present invention, high strength approximately
fan-shaped deformed wire cannot be stably produced.
[0076] As shown in Comparative Example No. 40, when the Si
segregation degree of the cementite/ferrite interface is more than
the range of the present invention, ageing during drawing
progresses, the workability becomes remarkably degraded, and
approximately fan-shaped deformed wire cannot be stably
produced.
Example 2
[0077] A 2t unit weight billet containing 0.82% C-1.0% Si-0.50%
Mn-0.0045% Al (Ceq=1.23%) was heated to 1050.degree. C., then
rolled to a wire diameter of 4.0 mm and air blast cooled at
7.degree. C./s or so to obtain a unit weight 2t wire rod coil
adjusted to a tensile strength of 1300 MPa. Next, the scale was
removed, then the wire rod was given a phosphor zinc coating. After
this, the wire rod was heated at 900.degree. C. for 1 minute, butt
welded, and cooled. The weld was reheated at 850.degree. C. for 1
minute, then cooled at a cooling rate of 10.degree. C./s, then the
rod was drawn by a die to 3.0 mm and cold rolled by rollers to a
rectangular cross-section wire rod of a thickness of 1.8 mm. Next,
to obtain the substantial fan shape, the rod was cold rolled by
rollers having approximately fan-shaped calibers to obtain
approximately fan-shaped deformed wire of a length of 60 km having
an outside diameter b: 5.2 mm, inside diameter a: 2.55 mm,
thickness t: 1.325 mm, tensile strength 1820 MPa, and pebbled
surface relief depth of an average 1 .mu.m.
INDUSTRIAL APPLICABILITY
[0078] The approximately fan-shaped deformed wire of the present
invention can be made the desired length by welding and further can
provide an extremely high strength, so can solve the problem of the
shallower depth of use accompanying an increase in weight of the
cable or decline in tension-bearing ability. Further, when used for
cables of the current structures, there is also the effect that use
at deeper depths becomes possible.
* * * * *